The Detroit Institute of Arts has tentative commitments for about 70 percent of its $100 million pledge to the “grand bargain” that could give the museum its independence and shore up Detroit pensions if approved by pensioners and, ultimately, the U.S. bankruptcy court.

Detroit’s carmakers today announced $26 million in grants to the museum, putting it over a quarter of the way to meeting its commitment. Ford Motor Co. Fund and General Motors Co./GM Foundation each contributed $10 million, and Chrysler Group LLC gave $6 million.

The DIA expects to announce within the next few weeks additional gifts from other corporations, private foundations and individuals that will put it at about 70 percent of its goal, Chairman Eugene Gargaro told Crain’s Monday morning.

The total pot of money for the grand bargain is at $819.5 million, but another $56 million in income stabilization funds to ensure pensioners don’t fall below the poverty line is expected to be added, said Chief U.S. District Judge Gerald Rosen, who serves as the lead mediator between Detroit and its creditors.

Once the DIA has met its commitment to the grand bargain, its priority goal will be to raise endowment, Gargaro said.

The museum hopes to secure another $275 million to add to its current endowment of about $100 million, Director Graham Beal said.

At an average rate of return of 5 percent per year, a $375 million to $400 million endowment would generate roughly $20 million each year in interest to help fund the DIA’s operations.

That means the DIA would have about eight years left under the 10-year millage approved by voters in Wayne, Oakland and Macomb counties in 2012 to raise $275 million while fundraising resources are freed up from having to raise the bulk of the museum’s operating money.

The millage is providing about $23 million annually now toward the museum’s operations.

“None of us wants to go through a millage again,” Beal said.

In the meantime, the DIA’s current endowment will also grow, he said.

“As long as we have the millage, we will not be taking anything from that.”